RFR: 8354242: VectorAPI: combine vector not operation with compare [v6]

[erifan]

On Thu, 29 May 2025 08:00:05 GMT, erifan <duke at openjdk.org> wrote:

>> src/hotspot/share/opto/vectornode.cpp line 2233:
>> 
>>> 2231:   if (in2->Opcode() == Op_VectorMaskCast) {
>>> 2232:     in2 = in2->in(1);
>>> 2233:   }
>> 
>> Wow, this seems to be an addition that is not covered in the patterns you mention above, right?
>> But is that even necessary?
>> I suppose here `in2 = VectorMaskCast(all_ones_vector)`.
>> Would we not already want to transform this pattern in `VectorMaskCast::Ideal`, is that not possible and more powerful?
>
> Oh yeah, I forgot to mention it in the above comment and commit message. 
> 
> Yes, this is for `in2 = VectorMaskCast(all_ones_vector)`.  I agree it's better to do this transformation in `VectorMaskCast::Ideal`. I'll remove this code change and do the `VectorMaskCast` optimization later. Thanks!

Done.

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PR Review Comment: https://git.openjdk.org/jdk/pull/24674#discussion_r2128344233